This invention relates to the art of recording images on thermal recording materials. More particularly, this invention relates to a package of thermal recording sheets containing at least one maintenance sheet for use in thermal head cleaning and a thermal image recording apparatus capable of cleaning a thermal head employing the maintenance sheet.
Thermal recording materials are commonly used to record the images produced in diagnosis by ultrasonic scanning. This recording method, commonly referred to as thermal image recording, eliminates the need for wet processing and offers several advantages including convenience in handling. Hence, the use of the thermal image recording system is not limited to small-scale applications such as diagnosis by ultrasonic scanning and an extension to those areas of medical diagnoses such as MRI and X-ray photography where large and high-quality images are required is under review.
As is well known, thermal image recording involves the use of a thermal head having a glaze in which thermal recording dots for heating a thermal recording material to record an image are arranged in one direction and, with the glaze in contact with the thermal recording material, the two members are moved relative to each other in a direction perpendicular to the direction in which the recording dots are arranged, as said dots are heated imagewise in accordance with the image to be recorded to heat the thermal recording layer, thereby accomplishing image reproduction.
Thus, the thermal head is kept in contact with the thermal recording material while image reproduction is performed and it is not uncommon that the temperature of the thermal head (glaze) reaches at least 200.degree. C. or more even in the normal recording mode. As a result, the fine dust particles depositing on the thermal recording material and the recording material itself will fuse, burn or undergo other thermal deterioration that increases the chance of thermal head staining. To remove the stain, the glaze surface and other areas of thermal head need be cleaned periodically.
With the prior art thermal recording apparatus, cleaning of the thermal head is a cumbersome and time-consuming work because the operator has to remove the stain on the glaze surface and other areas of the thermal head manually using a suitable means such as a cloth wetted with a liquid cleaner such as alcohol or a lapping sheet having a fine enough mesh and this is one of the causes of reduced efficiency in image reproduction. In addition, cleaning with the lapping sheet is essentially a process that polishes the glaze surface and if it is accomplished manually, irregularities may sometimes develop on the glaze surface.
What is more, the structural design of the thermal recording apparatus is such that the operational efficiency of cleaning the thermal head is low and it must sometimes be removed from the apparatus before it is cleaned.
A further problem with the prior art thermal recording apparatus is that the operator often forgets to clean the thermal head, so that the staining of the head aggravates until it fouls the recorded image. The irregularities on the glaze surface can be a cause of the production of defective images. Such image stain and defects not only result in the deterioration of the quality of finished images; they can also cause a serious problem in medical areas by leading to a wrong diagnosis.